
MOTOROLA
56
MC68CK338
MC68CK338TS/D
4.7 Background Debugging Mode
The background debugger on the CPU32L is implemented in CPU microcode. The background debug-
ging commands are summarized in
Table 34
.
Table 34 Background Debugging Mode Commands
Command
Mnemonic
Description
Read D/A Register
RDREG/RAREG
Read the selected address or data register and return
the results through the serial interface.
The data operand is written to the specified address or
data register.
The specified system control register is read. All regis-
ters that can be read in supervisor mode can be read in
background mode.
The operand data is written into the specified system
control register.
Read the sized data at the memory location specified
by the long-word address. The source function code
register (SFC) determines the address space access-
ed.
Write the operand data to the memory location speci-
fied by the long-word address. The destination function
code (DFC) register determines the address space ac-
cessed.
Used in conjunction with the READ command to dump
large blocks of memory. An initial READ is executed to
set up the starting address of the block and retrieve the
first result. Subsequent operands are retrieved with the
DUMP command.
Used in conjunction with the WRITE command to fill
large blocks of memory. Initially, a WRITE is executed
to set up the starting address of the block and supply
the first operand. The FILL command writes subse-
quent operands.
The pipe is flushed and refilled before resuming in-
struction execution at the current PC.
Current program counter is stacked at the location of
the current stack pointer. Instruction execution begins
at user patch code.
Asserts RESET for 512 clock cycles. The CPU is not
reset by this command. Synonymous with the CPU RE-
SET instruction.
NOP performs no operation and can be used as a null
command.
Write D/A Register
WDREG/WAREG
Read System Register
RSREG
Write System Register
WSREG
Read Memory Location
READ
Write Memory Location
WRITE
Dump Memory Block
DUMP
Fill Memory Block
FILL
Resume Execution
GO
Patch User Code
CALL
Reset Peripherals
RST
No Operation
NOP